(214k) Enhancing the Surface Reactivity of SrxY1-XTiO3 Mixed Ionic and Electronic Conductor Toward Fuel Oxidation in SOFC: First-Principles Study

In recent years, the yttrium-doped strontium titanium oxide (Sr_1-xY_xTiO₃) has received much attention as an alternative anode catalyst for solid oxide fuel cell (SOFC) due to its high sulfur/carbon resistance, good electronic/ionic conductivity and phase stability in typical SOFC anode operating conditions. However, Sr_1-xY_xTiO₃has exhibited the poor electro-catalytic activity toward fuel (i.e. H₂ or hydrocarbon) oxidation. Thus, it is very imperative to understand the factors controlling the reactivity of Sr_1-xY_xTiO₃ toward SOFC anode reactions for developing effective Sr_1-xY_xTiO₃-based anode materials.

In this work, we will present some recent theoretical results we have on the role of surface oxygen vacancy formation energy in determining the kinetics of H₂ oxidation. Using spin-polarized density functional theory calculations for geometric and electronic structures, we find that the H₂ oxidation reaction [H₂+O(surface) → OH+OH → H₂O+ O(vacancy)] on the surface of Sr_1-xY_xTiO₃ -based anode materials strongly depends on the oxygen vacancy formation energy. Our calculations also show the oxygen vacancy formation energy can be controlled by doping the transition-metal into the Ti lattice site of Sr_1-xY_xTiO₃.

 This work hints the importance of knowing how to properly tailor the surface reactivity of oxide-based anode materials for achieving wanted electro-catalytic activity for SOFC application.